Days of Christmas: The X-Men run into a new mutant

From the Marvel Holiday Special trade I have with which doesn't say if these are all reprints (which I assumed they were) or where they would come from. I'm pretty much done with Marvel superheroes except MC2 Spider-Girl and Scarlet Spider (both rarely appear.) I do remember this trade fondly and this story stood out.

" A miracle a few blocks down from 34th St."

Back in the X-Men era where Nightcrawler, Storm, Banshee, Wolverine, etc. were introduced the team finds out there's a mutant more powerful than any they encountered before. On the way they run into some foes. It's actually very charming although it can be a little horrifying if you think of the implication of action figures. (Especially considering another mini comic in this book called "--Zounds O' Silence.") Like all of the stories in the TPB this tale is short but very memorable. It's one of those plots that literally wouldn't be fitting outside of the Christmas timeframe.